News Release 344

Final sampling of Lake of the Ozarks study finds no elevated E. Coli levels

Volume 39-344 (For Immediate Release)
For more information: 573-751-1010

JEFFERSON CITY, Mo., OCT. 5, 2011 – The final water quality sampling of the Missouri Department of Natural Resources’ five-year study of the Lake of the Ozarks found no elevated E. coli.

Samples taken Monday found no cases of elevated E. coli in any of the 12 coves sampled on the lake’s western end.

The geometric mean for the 2011 recreational season at the coves sampled was 3 E. coli colonies per 100 milliliters of water, which was the lowest geometric mean since the study began in 2007. A geometric mean is a statistical method used to analyze data collected over a period of time.

All of the study’s year-end results have been significantly below the geometric mean at which a water body is considered unsuitable for swimming and related activities, which is 126 E. coli colonies per 100 milliliters of water. From 2007-2011 the geometric means were 5, 7.6, 8.8, 3.8 and 3.0.

Over the course of the study, the department, working with volunteers from the Lake of the Ozarks Watershed Alliance, collected and processed 1,619 samples from sites beginning at Bagnell Dam in 2007 and proceeding up the lake to Truman Dam this year. Over the five years of the study, 43 samples – or 2.6 percent – were in excess of the U.S. Environmental Protection Agency’s single sample maximum recommend E. coli level for swimming beaches, which is 235 E. coli colonies per 100 milliliters of water.

The Lake of the Ozarks study was funded by Ameren UE as part of the relicensing agreement for Bagnell Dam.

A link to a map of the 2011 sample areas and results is available on the department’s website at dnr.mo.gov/loz.htm. Sample results from previous years are also available online.

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